This paper presents the  available information  of the Red seabrem fishery in the 
Strait of Gibraltar  and updates the documents  presented in previous years  with 
the information  from the last  analyzed year,  2008. The document presents  data 
about landings, LPUE,  length frequencies and  also biological information  for 
Pagellus bogaraveo which should be used for its assessment.Versión del edito

Burgos, C. (Candelaria)

Canoura, J. (Jesús)

Farias, C. (Carlos)

Gil, J. (Juan)

English

This paper presents the  available information  of the Red seabrem fishery in the 
Strait of Gibraltar  and updates the documents  presented in previous years  with 
the information  from the last  analyzed year,  2008. The document presents  data 
about landings, LPUE,  length frequencies and  also biological information  for 
Pagellus bogaraveo which should be used for its assessment

Repositorio Institucional Digital del IEO

 1 Working Document to be presented to the ICES Working Group on the  Biology and Assessment of Deep Sea Fisheries Resources  ICES WGDEEP - Copenhagen 9-16 March 2009  The Red seabream (Pagellus bogaraveo) fishery in the Strait of Gibraltar: Data updated for assessment of the ICES Subarea IX. Juan Gil, Jesús Canoura, Candelaria Burgos and Carlos Farias Instituto Español de Oceanografía Centro Oceanográfico de Cádiz  Puerto Pesquero. Muelle de Levante s/n 11006 Cádiz, Spain  Abstract This paper presents the available information of the Red seabrem fishery in the Strait of Gibraltar and updates the documents presented in previous years with the information from the last analyzed year, 2008. The document presents data about landings, LPUE, length frequencies and also biological information for Pagellus bogaraveo which should be used for its assessment.  1. Introduction and fishery description Since the earlies 1980´s an artisanal fishery targeted to the red seabream (Pagellus bogaraveo, namely “voraz”) have been developing along the Strait of Gibraltar area (ICES IXa south). This fishery has already been broadly described in previous Working Documents presented to the ICES WGDEEP (Gil et al., 2000; Gil & Sobrino, 2001, 2002 and 2004; Gil et al., 2003, 2005, 2006, 2007 and 2008) and also in Silva et al.(2002). The Instituto Español de Oceanografía (IEO) began the study and the fishery monitoring following the request from the Fishermen Corporations. In 2006 and 2008, assessment trials were attempted within the ICES WGDEEP (ICES, 2006, 2008). The main objective of this paper is provide an updated summary of the current status of knowledge on the fishery and biology of this deep-water species in the area which allows a new assessment exercise in ICES area IX at the 2009 ICES WGDEEP meeting. 2. Material and methods Fishery information was gathered for the period 1983-2008 from the sale sheets: monthly landings, monthly number of sales and the number of days in which those sales were carried out. Moreover, from the beginning of the IEO monitoring, June 1997, an ad hoc monthly length samplings from the different commercial sizes are carrying out to estimate the landings length distribution (Gil et al., 2000).  2 Growth was studied throughout monthly samples from “voracera” fleet landings in the from 2003 onwards Whole otoliths (sagitta) were read under a light microscope to record the number of rings and their edge type. January 1st was assigned as birth date. From at least three agree readings were created one unique (combined) ALK. 3. Results and discussion 3.1. Fishery data  - Landings data: Figure 1 shows a continuous increase of the landings to a maximum in 1994. Since 1994 landings have gone decreasing, except in 1996 and 1997, till arise the lowest value of the recent years in 2002. Then, from 2003 onwards it shows an increasing trend till reached the highest value of the last years in 2008. - LPUEs: Fishing effort increases too (Figure 2). It is important to emphasize that the effort unit chosen cannot be too appropriate as do not consider the missing effort. Thus, in the recent years this missing effort increases substantially (fishing vessels with no catches and precisely why with no sale sheet to be recorded). This way it is advisable to interpret with caution the LPUE trend in the last years because it cannot be a real image of the resource abundance. - Landings length frequencies: The fishery resource suffers a decrease of the landed mean length (Figure 3) mainly from 1995 to 1998. It is necessary to point out that species probably does not have a homogeneous geographic and bathymetric distribution related to their length. This fact could explain the different landed mean length between ports (Tarifa and Algeciras). The mean length of the landings gets progressively increasing from 1999 onwards, but along the last years the trend varies increasing again from 2006 on in both ports. However the median value from these years remains under the mean in every case and close to the minimum landing size in Algeciras. 3.2. Biological data - Age and growth: Red (blackspot) seabream is considered a slow growing species. Gueguen (1969) reported a maximum age of 20 years. In the Azores Islands a maximum age of 15 years was observed in a 56 cm length fish (Krug, 1994).  An ALK was obtained by 1497 three agreed readings from otoliths collected from 2003 onwards. It covers lengths from 24 to 54 cm (Figure 4). ALK comprises ages between 3 and 10. Younger ages are well sampled while the older groups are susceptible to poorer estimates. Von Bertalanffy growth parameters estimates from this combined ALK are: L∞= 62 cm (fixed from the largest observed sample), k= 0.162 and t0= -0.337 (r2=0.94). From 1041 samples (r2=0.99), the relationship between the length of the individuals and its respective weight are:  3 Total Weight (g) = 0,014*[Total Length (cm)]3,014 -Natural mortality (M): The natural mortality of Pagellus bogaraveo is uncertain because there is no data available to estimate M directly. A mortality rate of 0.2 year-1 has been adopted by several authors in several studies in the Azores Islands (Silva, 1987; Silva et al., 1994; Krug, 1994, Pinho et al., 1999, Pinho, 2003). - Maturity: An annual reproductive cycle is defined for the species by Gil and Sobrino in 2001: The spawning season seems to take place during the first quarter of the year. The smallest specimina are mainly males, maturing at a L50=30.1 cm. Around 32-33 cm length an important part of individuals suffers a sexual inversion. Females maturing at L50=35.1 cm. Thus, from age 5 all individuals could be considered mature ones. 4. Conclusions Useful data for the assessment by age structured models, at least as an attempt. Catch-at-age fishery landings could be derived by the application of the combined ALK for the period 1990-2008. Mean weight of the catch could be estimated according to the ALK and the length-weight relationship proposed in this paper. Mean weight at age in the stock was considered equal to the mean weight at age in the catch. 0.2 year-1 could be adopted as a natural mortality value and considered it the same for all ages along the period studied. Female maturity ogive estimated by Gil and Sobrino in 2001 could be used and considered the same over time. Proportion of F and M before spawning could be considered 0 because the spawning season takes place in the first quarter of the year. The oldest age group (10) should be consider as plus group (10+) because at least one sample is recaptured 10 years later from its tagging. From this information Lowestoft software required files could be created to attempt VPA exploratory runs. Without tuning fleet information, Separable VPA could be used in order to define terminal F of the analysis. Acknowledgments We would like to express our most sincere gratefulness to all those institutions and people for his collaboration in the execution of the present work: - Instituto Español de Oceanografía - Consejería de Agricultura y Pesca de la Junta de Andalucía - People from the Fishermen Brotherhood and Fishmarket of Tarifa, for their readiness and facilities offered to obtain the required samples, especially to Juan José Rodríguez-Santander. - IEO Cádiz mates for their collaboration in the biological samplings and mainly to Ricardo Sánchez Leal (called Jordi) for his help in statistical matters.   4 References GUEGUEN, J., 1969. Croissance de la dorade, Pagellus centrodontus Delaroche. Revue du Travail de l´ Institut des Pêches Maritimes, 33 (3): 251-254. GIL, J., J. CANOURA, C. BURGOS & C. FARIAS, 2005. Update of the Red seabream (Pagellus bogaraveo) fishery data in the Strait of Gibraltar (ICES IXa south) including biological information. Work. Doc. to the 2005 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., J. CANOURA, C. BURGOS, C. FARIAS and V. POLONIO, 2008. Red seabream (Pagellus bogaraveo) assessment of the ICES IX from the information available of the fishery in the Gibraltar Strait. Work. Doc. to the 2008 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., J. CANOURA, C. BURGOS & I. SOBRINO, 2007. Red seabream (Pagellus bogaraveo) fishery of the Strait of Gibraltar (ICES IXa south): Update of the available information. Work. Doc. to the 2007 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., I. SOBRINO and M. P. JIMÉNEZ, 2000. A brief description of the Strait of Gibraltar red seabream (Pagellus bogaraveo) fishery. Working Document to the 2000 Report of the ICES S.G. on the Biology and Assessmnet of Deep-sea Fisheries Resources (SGDEEP). GIL, J. and I. SOBRINO, 2001. New biological information about the red seabream (Pagellus bogaraveo) of the Strait of Gibraltar (ICES IXa). Work. Doc. to the 2001 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J. and I. SOBRINO, 2001. Studies on reproductive biology of the Red (blackspot) seabream [Pagellus bogaraveo (Brünnich, 1768)] from the Strait of Gibraltar (ICES IXa/SW Spain). NAFO SCR Doc. 01/86. GIL, J. and I. SOBRINO, 2001. Studies on reproductive biology of the Red (blackspot) seabream [Pagellus bogaraveo (Brünnich, 1768)] from the Strait of Gibraltar (ICES IXa/SW Spain). NAFO SCR Doc. 01/86. GIL, J. and I. SOBRINO, 2002. Update of the information about the red seabream (Pagellus bogaraveo) from the Strait of Gibraltar (ICES IXa south). Work. Doc. to the 2002 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP).  5 GIL, J. and I. SOBRINO, 2004. Red seabream (Pagellus bogaraveo) fishery of the Strait of Gibraltar (ICES IXa south): Update of the information available. Work. Doc. to the 2004 Report of the ICES Working Group on the Biology and Assessement of Deep-Sea Fisheries Resources (WGDEEP). GIL, J., I.SOBRINO and J. CANOURA, 2003. Update of the information about the red seabream (Pagellus bogaraveo) fishery in the Strait of Gibraltar (ICES IXa south). Work. Doc. to the 2003 Report of the ICES Working Group on the Biology and Assessment of Deep-Sea Fisheries Resources (WGDEEP). ICES, 2006. Report of the Working Group on the Biology and Assessment of Deep-sea Fisheries Resources. ICES CM 2006/ACFM: 28. ICES, 2008. Report of the Working Group on the Biology and Assessment of Deep-sea Fisheries Resources. ICES CM 2008/ACOM: 14. KRUG, H., 1994. Biologia e avaliação do stock açoriano de goraz, Pagellus bogaraveo. PhD thesis. Department of Oceanography and Fisheries, University of the Azores, Horta. Arquivos do DOP, Série estudos, No.7/94. 192 pp. PINHO, M. R., 2003. Abundance estimation and management of Azorean demersal species. Phd thesis. Department Oceanography of Azores. University of the Azores, Portugal. 163pp. PINHO, M. R., G. MENEZES and H. KRUG, 1999. Estado de exploração dos recursos demersais dos Açores – Proposta de gestão. Relatório apresentado ao Workshop:”Gestão de Pescas”, Secretaria Regional de Agricultura Pescas e Ambiente, Direcção Regional das Pescas. Horta 20 de Março de 1999. SILVA, H. M., 1987. Estado dos stocks de goraz e abrótea. In Relatório da VII Semana das Pescas dos Açores, pp.197-199. Ed. by Secretaria Regional de Agricultura e Pescas, Direcção Regional das Pescas dos Açores, Horta, Açores. 269 pp.  SILVA, L., J. GIL and I. SOBRINO, 2002. Definition of fleet components in the Spanish artisanal fisheries of the Gulf of Cádiz (SW Spain, ICES Division IXa). Fisheries Research 59 (2002):117-128. SILVA, H. M., H. KRUG, and G. MENEZES, 1994. Bases para a regulamentação da pesca de demersais nos Açores. Arquivos do DOP, Série estudos, No./94.  SOBRINO I. and J. GIL, 2001. Studies on Age Determination and Growth Pattern of the Red (Blackspot) Seabream [Pagellus bogaraveo (Brünnich, 1768)] from the Strait of Gibraltar (ICES IXa/SW Spain): Application to the Species Migratory Pattern. NAFO SCR Doc. 01/87.  6    Figure 1. Pagellus bogaraveo of the Strait of Gibraltar: Landings (1983-2008).    Figure 2. Pagellus bogaraveo of the Strait of Gibraltar: Evolution of the chosen effort unit and estimated LPUE (1983-2008).    7      Figure 3. Pagellus bogaraveo of the Strait of Gibraltar: Evolution of the landings length distribution descriptive statistics.   8   Length/Age 3 4 5 6 7 8 9 10 Total 24 5 0 0 0 0 0 0 0 5 25 5 0 0 0 0 0 0 0 5 26 7 0 0 0 0 0 0 0 7 27 8 1 0 0 0 0 0 0 9 28 14 5 0 0 0 0 0 0 19 29 30 26 1 0 0 0 0 0 57 30 59 54 6 0 0 0 0 0 119 31 48 74 3 0 0 0 0 0 125 32 33 88 21 0 0 0 0 0 142 33 21 92 24 0 0 0 0 0 137 34 20 69 39 4 0 0 0 0 132 35 9 38 52 1 1 0 0 0 101 36 6 34 54 5 0 0 0 0 99 37 4 22 33 19 2 0 0 0 80 38 2 10 35 38 2 0 0 0 87 39 0 10 26 39 8 0 0 0 83 40 0 4 16 20 11 0 0 0 51 41 0 0 9 14 12 0 0 0 35 42 0 1 5 19 26 2 0 0 53 43 0 0 2 13 9 2 1 0 27 44 0 0 0 6 16 2 0 0 24 45 0 0 0 1 12 6 1 0 20 46 0 0 0 0 3 9 2 0 14 47 0 0 0 0 0 8 3 0 11 48 0 0 0 0 1 8 2 0 11 49 0 0 0 0 1 6 4 0 11 50 0 0 0 0 0 4 5 2 11 51 0 0 0 0 0 1 4 3 8 52 0 0 0 0 0 0 2 4 6 53 0 0 0 0 0 0 4 3 7 54 0 0 0 0 0 0 0 1 1  Figure 4. Pagellus bogaraveo of the Strait of Gibraltar: ALK obtained by means of at least agreed readings (otoliths from 2003 to 2008 samples).  

The red seabream (Pagellus bogaraveo) fishery in the Strait of Gibraltar: Data updated for assessment of the ICES Sub area IX

Gil, Juan

Canoura, Jesús

Burgos, Candelaria

Farias, Carlos

Digital.CSIC

http://www.repositorio.ieo.es/e-ieo/bitstream/10508/3504/1/WD%20Strait%20of%20Gibraltar%20Red%20seabream_2009.pdf

The red seabream (Pagellus bogaraveo) fishery in the Strait of Gibraltar: Data updated for assessment of the ICES Sub area IX

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